UsageRules is a development tool for Elixir projects that:
- helps gather and consolidate usage rules from dependencies to provide to LLM agents via
mix usage_rules.sync - provides pre-built usage rules for Elixir
- provides a powerful documentation search task for hexdocs with
mix usage_rules.search_docs
# install usage_rules into your project
mix igniter.install usage_rules
# swap AGENTS.md out for any file you like, e.g `CLAUDE.md`
# sync projects as links to their usage rules
# to save tokens. Agent can view them on demand
mix usage_rules.sync AGENTS.md --all \
--inline usage_rules:all \
--link-to-folder depsYes, and we have data to back it up: https://github.com/ash-project/evals/blob/main/reports/flagship.md
You'll note this package itself doesn't have a usage-rules.md. Its a simple tool that likely would not benefit from having a usage-rules.md file.
usage-rules.md is not an existing standard, rather it is a community initiative that may evolve over time as adoption grows and feedback is gathered. We encourage experimentation and welcome input on how to make this approach more useful for the broader Elixir ecosystem.
Even if you don't want to use LLMs, its very possible that your users will, and they will often come to you with hallucinations from their LLMs and try to get your help with it. Writing a usage-rules.md file is a great way to stop this sort of thing 😁
We don't really know what makes great usage-rules.md files yet. Ash Framework is experimenting with quite fleshed out usage rules which seems to be working quite well. See Ash Framework's usage-rules.md for one such large example. Perhaps for your package or framework only a few lines are necessary. We will all have to adjust over time.
One quick tip is to have an agent begin the work of writing rules for you, by pointing it at your docs and asking it to write a usage-rules.md file in a condensed format that would be useful for agents to work with your tool. Then, aggressively prune and edit it to your taste.
Make sure that your usage-rules.md file is included in your hex package's files option, so that it is distributed with your package.
A package can have a package-rules.md and/or sub-rule files, each of which is referred to separately.
For example:
package-rules.md # general rules
package-rules/
html.md # html specific rules
database.md # database specific rules
When synchronizing, these are stated separately, like so:
mix usage_rules.sync AGENTS.md package package:html package:database
- Dependency Rules Collection: Automatically discovers and collects usage rules from dependencies that provide
usage-rules.mdfiles in their package directory - Rules Consolidation: Combines multiple package rules into a single file with proper sectioning and markers
- Status Tracking: Can list dependencies with usage rules and check if your consolidated file is up-to-date
- Selective Management: Allows adding/removing specific packages from your rules file
- Documentation Search: Search hexdocs with human-readable markdown output using
mix usage_rules.search_docs- designed to help AI agents find relevant documentation
- The tool scans your project's dependencies (in
deps/directory) - Looks for
usage-rules.mdfiles in each dependency - Consolidates these rules into a target file with special markers like
<-- package-name-start -->and<-- package-name-end --> - Maintains sections that can be updated independently as dependencies change
This is particularly useful for projects using frameworks like Ash, Phoenix, or other packages that provide specific usage guidelines, coding patterns, or best practices that should be followed consistently across your project.
The main task mix usage_rules.sync provides several modes of operation:
There are two standard ways to use usage_rules. The first, is to copy usage rules into your project. This allows customization and visibility into the rules. The second is to use the rules files directly from the deps in your deps/ folder. In both cases, your rules file is modified to link to the usage rules files, as a breadcrumb to the agent.
This will create a folder called rules, with a file per package that has a usage-rules.md file. Then it will link
to those from you rules file.
mix usage_rules.sync AGENTS.md --all \
--link-to-folder deps \
--inline usage_rules:allThis will add a section in your rules file for each of your top level dependencies that have a usage-rules.md. It is
simply a breadcrumb to tell the agent that it should look
in deps/<package-name>/usage-rules.md when working with
that package. This will not overwrite your existing rules, but will append to it, and future calls will synchronize those contents.
mix usage_rules.sync CLAUDE.md --all --link-to-folder depsmix usage_rules.sync rules.md ash phoenixmix usage_rules.sync CLAUDE.md --allmix usage_rules.sync --listmix usage_rules.sync CLAUDE.md --listmix usage_rules.sync CLAUDE.md ash --removemix usage_rules.sync CLAUDE.md ash phoenix --link-to-folder rulesmix usage_rules.sync CLAUDE.md ash phoenix --link-to-folder rules --link-style atmix usage_rules.sync CLAUDE.md ash phoenix --link-to-folder depsmix usage_rules.sync CLAUDE.md --all --link-to-folder docsThe mix usage_rules.search_docs task searches hexdocs with human-readable markdown output, specifically designed to help AI agents find relevant documentation.
# Search documentation for all dependencies in the current mix project
mix usage_rules.search_docs "search term"
# Search documentation for specific packages
mix usage_rules.search_docs "search term" -p ecto -p ash
# Search documentation for specific versions
mix usage_rules.search_docs "search term" -p [email protected] -p [email protected]
# Control output format and pagination
mix usage_rules.search_docs "search term" --output json --page 2 --per-page 20
# Search across all packages on hex
mix usage_rules.search_docs "search term" --everywhere
# Search only in titles (useful for finding specific functions/modules)
mix usage_rules.search_docs "Enum.zip" --query-by title
# Search in specific fields (available: doc, title, type)
mix usage_rules.search_docs "validation" --query-by "doc,title"Organizes usage rules into separate files for better management of large rule sets.
Options:
--link-style markdown(default):[ash usage rules](docs/ash.md)--link-style at:@docs/ash.md(optimized for Claude AI)--link-to-folder deps: Links directly todeps/package/usage-rules.md(no file copying)
Examples:
# Create individual files with markdown links
mix usage_rules.sync CLAUDE.md ash phoenix --link-to-folder docs
# Use @-style links for Claude AI
mix usage_rules.sync CLAUDE.md ash phoenix --link-to-folder docs --link-style at
# Link directly to deps without copying
mix usage_rules.sync CLAUDE.md ash phoenix --link-to-folder depsmix igniter.install usage_rules.
Add the dependency manually
def deps do
[
# should only ever be used as a dev dependency
# requires igniter as a dev dependency
{:usage_rules, "~> 0.1", only: [:dev]},
{:igniter, "~> 0.6", only: [:dev]}
]
end